Swipe down from the top of the screen twice to open Quick Settings
Look for Screen Record or Screen Recorder
If it is not visible, tap Edit or the pencil icon and add Screen Record
Tap Screen Record
Choose audio options if prompted
Tap Start or Start recording
Wait for the countdown
Use your phone normally while recording
Swipe down and tap Stop in the recording notification when finished
Find the video in Photos, Gallery, or Files
If your phone has no built-in recorder, install a trusted screen recorder app from the Play Store